Method of and apparatus for exploding armor piercing projectiles



H. J. NICHOLS 2,441,897

METHOD OF AND APPARATUS FOR EXPLODING ARMOR PIERCING PROJECTILES May 18, 1948.

s sheets-sheet 1 Filed Oct. 25, 1952 i VQAI wm En um ./M M l w l R .u i mw a .m m/ wf] l .f a H m a Q nl u A ATTORNEY May 18, 1948. H J, NICHQLS 2,441,897

METHOD OF AND APPARATUS FOR EXPLODING ARMOR PIERCING PROJECTILES Filed Oct. 25, 1932 5 Sheets-Sheet 2 May 18, 1948. H, 1 NlCHOLs 21,441,897

METHOD OF AND APPARATUS FOR EXPLODING ARMOR FIERCING PROJECTILES -Filed Oct. 25, 1932 3 Sheets-Sheet 3 INVENTOR BY Har/7 //`a/ .ATTORNEY ?atented May 18, 1948 METHOD OF AND APPARATUS FOR EXPLOJD- ING ARMOR PIERCING PROJECTILES Harry J. Nichols, Dayton, Ohio, assigner to the United States of America as represented by the Secretary of the Navy Application October 25, 1932, Serial No. 639,505

(Cl. E-'75) 7 claims. 1

My present invention relates to new and useful improvements in a method of and apparatus for exploding armor piercing projectiles for substantially increasing'their efficiency and rendering certain the delaying of their explosion until after they have passed through the armor.

Explosive projectiles of the armor piercing type heretofore used have proved unsatisfactory for the'reason that the great force of their flightimpact upon armor and/or the distortion of the projectile due to such impact as Well as to the penetration of armor, especially at a substantial angle, causes such friction due -to the 4consequent changes in position of the contacting particles of compressed explosive as to detonate such explosives, usually when the same is entirely outside of or partially entering the armor and ordinarily without `obtaining the substantial effect which such explosion would have produced within the armored area.

In some types of Warfare projectiles detonating upon flight-impact are desirable and many such devices have been provided therefor, but in naval warfare such projectiles are ordinarily undesirable and with modern armor they are practically useless.

I have heretofore devised an explosive filler for a projectile which will not-be detonated by the flight-impact of its projectile upon armor due to its projectile piercing armor even at a substantial angle. That invention forms the subject-matter of my co-pending application Serial Number r708,106, now Patent No. 1,848,193. This application provides a method and means to make certain the explosion of such filler after passing through the armor.

The basic objects of my present invention are to provide a method of and apparatus for practicably and dependably withholding detonation upon minor night-impacts, dividing the steps of detonation into two of Which the rst is the initiation of detonation preceding the projectile eX- plosion by a time interval, initiating detonation only upon a major flight-impact, and variably delaying said time interval by and/or proportionately to the various rates of deceleration which the velocity of the projectile in ight may possibly encounter incident to major iiightimpacts; all preferably by one and the same production, and production-assembly, of projectiles without the necessity of any subsequent manual adjustment.

`My new and improved method relative to armor piercing projectiles containing explosive charges, may be stated to contemplate and include the steps of (l) uniformly constructing and adjusting thesame; (2) withholding the initiation of detonation and/or deiiagration of the explosive content upon the minor night-impacts of such projectile; (3) permitting such initiation only upon a major flight-impact of such projectile; (4) variably delaying the initiation of detonation relatively to the different decelerations of similar projectiles incident to piercing armor of different deceleration characteristics, and then accomplishing said initiation; (5) exploding the projectile.

My said method also contemplates that the explosive content which initiates detonaticn and that which ultimately explodes the projectile may be separated from each other and relatively movable and that such relative movement shall be in a direction opposite that of the flight of the projectile.

My apparatus contemplates and includes a projectile adapted to pierce armor even at a substantial angle and adapted to contain a major Volume of explosive, preferably that disclosed in.

my said co-pending application; a fuse and a booster charge each independent of and normally non-communicating with the other; means for relatively movably confining the fuse and the charge whereby they may be brought into communication with each other, this relative movement being mainly in a direction substantially different from, or opposite to, that of the ilight of the projectile; means for producing the relative movement; means for releasably restraining such movement during minor night-impacts of the projectile; means for variably delaying the actuation of the released actuating means; means for initiating detonation of the fuse by or at substantially the culmination of the relative movement; and means for variably delaying the deflagration, each of the Variable delay means being adapted to delay by, or in substantial synchronism with, the dilerences in the deceleration forces'incident to similar projectiles piercing armor of substantially different deceleration characteristics; means for locking each of said initiating means and said restraining means respectively in an unarmed and in a restraining position as Well as respectively in an armed and in`a released position.

These and other objects and exemplications of my invention will be more apparent from the following detailed description and the accompanying drawings illustrating one embodiment of my invention in an improved apparatus, of the many different forms and characters of appara- 3 tus each of which may be employed in the advantageous practice of my improved method, and each of which like characters of reference denote the same part.

In the drawings,

Figure 1 represents a central longitudinal sectional view of a fuse unit for an armor piercing projectile constructed and functioning in accordance with my invention, and illustrating the parts in their uniformly constructed and adjusted positions which are maintained under all circumstances until after the initiation of the flight'of the projectile;

Figure 2 is a view substantially similar to Figure 1 but showing the fuse-carrier unit not in section and illustrating the positions of the parts released and assumed in the flight of the projectile;

Figure 3 is a View of the forward portion of and substantially similar to Figure 1, but showing the relative position of the parts released and assumed upon a major impact of the projectile;

Figure e is substantially a composite of Figures 1 and 2, but showing the further different relative position of the parts upon the initiation of detonation of the fuse;

Figure 5 is an enlarged centrai vertical sectional View of the cap I i i3 Figure 6 illustrates the cap shown in Figure 5 as viewed from the end that faces the fuse;

Figure 7 is an enlarged sectional view on line 1--1 of Figure 1;

Figure 8 is an enlarged sectional View on line 8,*8 of Figure 2;

Figure 9 is an enlarged central vertical sectional view of the fuse carrying unit showing tube HG2 positioned by a major impact;

Figure 10 is an enlarged central vertical sectional view of the firing pin shown located, in its armed position;

Figure l1 is a front elevation view of a meniber of the fuse unit receiving the iiame from the detonating cap.

The device as a unit is preferably formed of a central cylindrical element i8 having a plurality of preferably outwardly flared openings I9 extending radially through the Wall element I8 and equally disposed about the periphery thereof. At the center of element VI is a cylindrical bearing opening `Eil extending longitudinally of element I8. At the forward end of element I 8, opening 29 communicates with an enlarged cylindrical opening 2i extending' to the forwardn end of element i8. Substantially coextensively with opening 2! the element i8 is reduced in diameter and is provided with external screw threads 22 terminatingrin a preferably square shoulder 2:3. The rear of opening communicates with a central longitudinal opening 24 in element I8 terminating preferably in an enlarged centrallongitudinal opening 25 whose rearward internal termina] is provided with screw threads 26 of desired extent. Intermediate openings 29 and 25 is a shoulder 21 which is preferably formed of a Vsubstantial taper.

The openings i9 terminate cylindrical openings 28 extending between and connecting bearing opening 29 and flaring openings I9 (Figure '7). Fitted within each opening .-23 is a cup 29 preferably of thin copper whose closed end is adjacent the periphery of opening v2! but does not extend thereinto. The edges of the cup 2-9- are flared outwardly to conform to and iit against the adjacent walls of their respective openings I9.

The fuse is formed, in the instance shown, of a cylindrical member 3U adapted to slide in bearing opening 29 of unit I8 that is provided with a shoulder 3l substantially conforming to shoulder 21 of unit IS. Shoulder 3| terminates in an integral enlarged cylindrical portion `32 having an enlarged head 33 upon its rear portion. A relativelyqheavy .coiled spring 34 is loosely mounted upon portion 32 and is adapted to exert its thrust between base 33 of the fuse and the shoulder `'.55 at the forward end of opening 24.

At a plurality of points about base 33 are secured radial pins 36, functioning as keys and adapted to slide each in their respective key- Ways 31 formed in the Wall of opening 24, An annular groove 38 is formed at the forward end of key-Ways 31 and of greater depth than the key- IWays formconvenience in machining. The cooperating pins 36 and key-Ways 31 hold the fuse from rotary movement but permit movement of the fuse in casing IB in a longitudinal direction. Extending peripherally about bearing 3i] near its forward end is a preferably circular groove 39, whose rearward edge is normally adapted to be in s ubstantial alignment with the shoulder 40 at the. junction of Vopenings v2li and EI. A plurality of balls i4I are mounted in said groove 39 and are retained therein by a ball race consisting, in the instance shown, of a portion of the interior surface of a longitudinally ldisposed cup-shaped cavity 43, formed in the rear end of retaining member 44 disposed in opening 2|.

VIn base 33 of the'fuseis a peripheral groove 45 (Figure 2) having mounted therein a plurality of segments 46 of a ring as shown in Figure 8. The segments 46 .are adapted to t loosely in groove 45 so that the centrifugal force ofthe projectile lrevolving about its longitudinal axis in its flight, .due to the rifles of the gun barrel from which it was projected, will cause segments 46 to bear outwardly against the wall of opening 24, while the fuse is being moved rearwardly relatively to element I8. In such position the fuse unit is locked by segments 4S bearing against the side of groove '.45 and against the forward shoulder 47 between openings 24v and 25, as hereinafter explained. Formed in the outer periphery of retainer 44 is a peripheral groove 48 mounting a plurality of segments 49, respectively similar to 4.5 and 46 heretofore described. Segments 49 are adapted, by the centrifugal force of the flight, of the projectile, to bear outwardly'against the wall of opening 2 I, and whenretainer 44 is moved forwardly,

Y as will hereinafter be described, segments 49 will likewise engage the wall of enlarged opening 59, formed at the mouth of opening 2Iv, and lock retainer 44 in position by the engagement of segments 49 against the shoulder 5I at the junction of openings ZI and 50.

o Threads 22 engage corresponding threads in the mouth of a cup- 52' that has acentral longitudinal opening 53 therein, preferably a continuation of opening 53, and a centrally disposed longitudinally extending opening V5,4 forwardly of and of lesse);` diameter Vthan opening 53. The forward end of retainer 44 is formed of a cylindrical integral pin 55 that is slidable into opening v54. Between the pinV 55'and retaining portion 4.4 is a shoulder 56 adapted to engageshoulder 51 between openings 53.. and 54 as hereinafter described. On the forward: end of pin 55 is a poraion r58v of reduced diameter adapted to be normally engaged by the inner ends of a plurality of pins-,59, each slidably Amounted in a `hole extending radially from the outer surface of cup 52 into opening 54. Each of pins 59 is provided crown of thimble 83.

--mouth 94.

with a central longitudinal opening 60 that extends from its outer end and contains a coil spring 6| bearing against the bottom of opening 60 and against a member 62 adapted to close the outer plosive content of the projectile, is -preferably formed of the explosive composition forming the subject matter of my co-pen'ding application Serial No. 708,106. A cupped shell 64' of relatively thin metal encloses cup- 52 and extends over the forward portion of fuse element I8 to a point rearwardly of the booster charges 66. At its edge and at a plurality of points in its length' shell 64 is spun or swaged into peripheral depressions 65 formed in said parts I8 and 52 for the purpose of retaining booster charges 66 in their respective openings |9 as well as further preventing the separation of parts |8 and 52 and retaining heads 62 against the thrust of springs 6 I.

Into the threaded opening 26 is screwed the threaded forwardly projecting end .61 of cylindrical body 68 provided with externally th'readed portion I1 and rear terminal flange 10.

Referring to Figure 10, in end 61 is formed a central longitudinal opening 1|, terminating in a conical bottom 12 from which is substantially centrally rearwardly extended an opening 13 adapted to receive a plurality of balls 14, as shown in Figure 1. In opening 1I is mounted to slide freely the enlarged head 15 of a firing pin 16, having a conical portion 11 conforming to the shape of bottom 12. Intermediate pin 16 and its head 15 is a cylindrical portion 18. Enlarged threaded mouth 19 of opening 1| receives a threaded plug 80 provided with a central aperture therethrough in which pin 16 is slidable, and having pin-holes 8l in its forward face adapted to receive the prongs of a Spanner wrench for fitting and removing said plug 80.

Extending radially from the outer periphery of end 61 are a plurality of openings 82 in each of which is mounted a relatively thin thimble 83 within which is slidably mounted a pin 84 having a centrally disposed outer cavity to receive coil spring 85, to exert pressure between pin 84 and a central positioning projection formed in the The inner end 81 of each pin 84 is preferably of .a reduced diameter and slidably extends through an opening in the inner end-wall of its thimble 83.

The internal construction of the fuse will now be described with reference to Figures 1, 3, 4, but particularly to enlarged view Figure 9. This unit has a central longitudinal opening 90, provide-d with an enlarged mouth 9|, in portion 30 and extending substantially therethrough, From the bottom or rearward end of opening 90 extends an opening 92, of smaller diameter than opening 90. Opening 92 is joined at its rearward terminal with an enlarged central, longitudinally disposed opening 93 having an enlarged threaded A round collar |00, having gasket ring |I seated upon its forward end, is mounted in the bottom of opening 93 with gasket |0| firmly pressed against the shoulder between communieating openings 92 and 93,- Extending longitudinally through the center of collar |00 is a tube |02 having a. tapering forward portion |03 fitting into a corresponding tapering hole through collar |00. In the initial assembly, tuber|02 is inserted merely to a nominal extent into the collar ,(see Figure 1) and is capable of being forced to different depths into or through said collar |00 (see Figure 9) as hereinafter explained. The longitudinal opening through tube |02 is open at its forward end and is closed at its rear end. Near the rearward end of tube |02 are formed a plurality of radial openings 04 through the wall of tube |02, In the rearward end of collar |00 is formed an enlarged centrally disposed longitudinal cavity adapted to receive a relatively short length of tubular compressed powder or other explosive |05 which extends over the rear end of tube |02 and over the openings |04 through the walls of tube |02, Mounted in opening 93 and against the rear surface of collar |00 is a sleeve ||0, closed at its forward end and having in the closure a centrally disposed longitudinal opening |06 adapted to slidably receive, as shown in Figures l and 13, the rear end portion of tube |02 which projects rearwardly of powder-tube |05. Surrounding opening |06 are a plurality of holes |01 extending longitudinally through the forward wall of said sleeve IIIJ and into a chamber III centrally and longitudinally disposed in the rear end of sleeve ||0. In the forward face of collar ||0 and surrounding opening |06 is an annular groove ||2. Against the rear end of sleeve lli) is mounted a disk I|5 having centrally disposed longitudinal opening ||6 therethrough. Screwed to the mouth 94 of opening 93 is a plug ||1 provide-d with a centrally disposed longitudinally extending cavity adapted to receive the detonating cap ||8 and the central opening ||9 therethrough for the passage of firing pin 16 when the firing pin is thrust through opening ||9 to fire cap ||8.

In the opening 92 is placed an explosive preferably in the form of granulated powder. Opening receives an explosive charge which may consist of compressed powder or other explosive contained in a relatively soft copper shell |20 whose forward end is open andis retained in the shell |20 by a wad |2|, which may be of paper or very thin copper, with the mouth of shell |20 crimped over the edges of wad |2|. Extending radially from the outer surface of member 30 and adjacent the groove 39, in which are balls 4|, are a plurality of radial openings terminating against the shell |20, each of which contains a compressed powder or other explosive pellet |22. Against the end of shell |20 is mounted a detonator seat wad |23, preferably of soft material and held in position by steel or other metallic wads |24 held in place by the mouth of opening 9| the latter being spun or swedge-d thereover,

The detonating cap H8 will now be described, reference being had more particularly to Figures 5 and 6. The detonating pellet |30 is mounted in the bottom of a thin metallic cup |3|, swedged against a portion of the outer surface of a metallic disk |32 having a centrally Idisposed projecting anvil surface |33 adapted to contact with the top surface of detonating pellet |30. Surrounding anvil portion |33 is one or more preferably inflammable washers |34 extending between disk |32 and detonating pellet |30 and protecting the pellet, before assembly, from exposure to the elements through a plurality of openings |35 extending through said disk |32.

Before detailing the operation of the parts and units in their various positions, it should be unalleine? causing theheated gases torheat and force Yor burn their way through wadv or wads lHifiand Openings |35 through disk L32, thence through central openings `l i6 in disk |7637 to chamber Hl and thence through holes l'i to annular groove .v H2 `wherejthe rearwardlredge 'of powdertube |05 is deflagrated This deiiagraticn :of tube m5 progresses at a deiiniterate and its generated Vgases,accumulate yin chamber H open-ings V| |16 and 4| |19 which are of suicient volume toV permit deagration of tube |65. When the deflagration of tube |65 has reached the depth to. which openingsi of tube |52 may be within the deflagrating tube |85, theinarnmable gases therefrom are forced through openings |84 into the hollow `of tube |82 tothe powder granules in opening 92, whose deagration is transmitted through wad |2| Ito and detonates the content of ,shell |20 which detonates the pellets |22.

If the detonation be initiated spontaneously, or otherwise than intended by the design Aand construction of this method and apparatus, the pellets l22 willbe in the position shown in Figure l which will be out of communication with each of the booster charges and the projectile will consequently not be exploded, but the gases from the above stated detonation will be contained in the cavities specified and those forward of the fuse bearing unit which are ample to care for the same without tendency todisrupt inembers I8 and 52 or otherwise detonate the eXplo- Y sive ,content or the projectile.

However, if in the course of the aforesaid det- `onation pellets |22 substantially register with caps 28, then, and then only, will the booster charges'. vG6 and the explosive content be detonated by the exciting of the caps v28 or the application of the force and/or intense heat oi the detonation being transmitted to and through the caps 218 to the booster charge G5 and thence to the explosive content ofthe projectile. Y

The tube |05 is preferably formed of powder, or the like, pressed into a tubular mass which burns more slowly than loose powder.

The hollow of the tube s2 is preferably f lled with granular powder, or the like, asV shown in Figures. l. and 3, some of which is scattered linto the mouth of the tapering hole through collar Y Hi8 and into the bore `oi tube il by the firing ofthe projectile. contenty of tube Q2 which may have been conned therein :for a vsubstantial period and which may have tended to arnalgarnate or cake.

What is called creep will, during the fiight of the projectile, cause the content of tube 92 to pack against the wad |2| oi |255. A minor impact of the projectile will further nach and solidify the content of tube 92` against Vwad |21. A major impact of the projectile will still 44, and to proportion the same such that .the

bursting of the projectile is attained at approximately the same distance behind the several This shakes andloosens up thicknesses `of armor ordinarily employed in the construction of ships of war. Y The 4 disk A|32 is provided with a recess |32a, in its forward face communicating with openings 35 (Figures 5 and 6) and H6 (Figure 9) to form a passageway for the burning .gases formed by the detonation disk |33, Intermediate metallic wad H5 and cap I8 is provided adeflagrating wad Hilo, (Figure 9) having a Acentral aperture therethrough in alignment with opening H5.

Openings Illa (Figure 9) in the rear face of plug |l ,accommodate the prongs of a Spanner wrench Lfor.convenient placing and possible removal of plug 4I il'.

`In lthe shouldered joint between body @il and memberV 8 is provided a. pin to prevent the Vunserewing of the threaded connection .between members t8 and I8.

vvIn the .rear surface of body 6.8 is formed a central longitudinal opening Uil) (Figure l) having an enlarged rear threaded mouth lill adapted to receive at will either a suitable screw plug to close `the opening `or a tracer-fuseunit IM having threaded rear portion adapted to be engaged by threads iM to retain the same position. Unit M2 is provided with va central longitudinal cavity extending from its rear -face Ytor the reception of a delagrating medium M3 in its for ward end, booster vcharge lll/1 in its rearward por tionl sealed by wad |45 preferably of thin copper or deflagrating material held in position by metallic wald lfl having central opening |47 therethrough and crimped or swaged in the mouth of opening lds. Vhen the projectile is ilredironi the gun the hot gases pass through Vopening It? and cause the deagration of booster charge |64 and tracer-fuse M3, affording a flameof any desired color issuing through opening M? to form a suitably colored flaming path by which the actualtrajectory of the projectile may be readily observed. Y

Upon the shell being red, the force of the explosion suddenly imparts a high velocityto the projectile which causes par-ts 'i5 and @A to be pressed more firmly agrainstetheir respective seats l2 and 4&1, and whichforces would tend to move the fuse'rezarwardly but for the balls 4| pre" venting such movement. In the flight of projectile, the friction of the Yair or other medium traversed 4by the projectileV tends shg'ntly to decelerate the velocityoi the projectile, while the rotary motion of fthe projectile due to the rifling of Vthe gun barrel, imparts rotation to the projectile about its longitudinal axis. The

deceleration of the projectile is not imparted to the firing pin 'l and its integral parts, with the result that they will thereby be moved forwardly from the `unarmed position shown in Figure l to the .armed position shown in Figure 2, due to the centrifuga1 force ci the projectile overconying the power of and compressing springs P5 and withdrawing the inner ends 8l of pins 813 from `interference with such movement of pin 'it and the flight Vof the projectile.

The centrifugal force of the projectile in flight .also overcomes the forceof springs 6| and moves pins 59 radially outwardly and free from shoulder 58 of retainer 45?, as shown in Figure 2, so that retainer 44 may be moved forwardly by an appropriate force.

If during its flight, the projectile should effect a minor fiight impact, which 'herein contemplates an Iimpact with water in a naval engagement for instance, or with a relatively frail object upon land, the flight velocity of projectile I 'will thereby be decelerated but the force of such deceleration will be insufficient to change the position of the parts substantially from that shown in Figure 2, which coincides with that illustrated in Figure 1 in all substantial respects except as to pins 16, 59 4and 81 as well as of balls M When the projectile makes a major night-impact, which is herein contemplated as being an impact with armor, the projectile is decelerated thereby at a rate substantially different from that of its possible deceleration incident to a minor flight-impact.

The deceleration force incident to a minor flight-impact is, by the design and construction of the parts, insufficient to release the fuse, but the greater deceleration force incident to a major night-impact is the only agency which can re- I lease the fuse Afrom its secured position illustrated in Figures 1 and 2.

In the position shown in 'Figures l and 2 the relatively heavy spring 34 is maintained under substantial compression by the balls 4| occupying groove 39 about the forward end of the fusecarrying unit and by those balls in that position bearing against shoulder 40 and being retained in such position by retainer 44, against whose surface 42 the balls 4| exert substantial outward pressure in holding the fuse against rearward movement by the force of spring 34. When the projectile attains a major flight-impact the deceleration force thereof overcomes the restrained force of spring 34 and causes the fuse to be moved forwardly until shoulders 21 and 3| are in contact. This forward movement of the fuse frees the contact between balls 4| and shoulder 40 which frees balls 4| from outward pressure against the surface 42 of retainer 44, due in effect to the normal wedge-like action -of curved groove 39 tending to move the balls 4| radially Ioutwardly against shoulder 40 by the normal force of spring 34 exerted upon balls 4| through groove 39. Normally it is the force of spring 34 which causes the outward pressure of balls 4| against the surface 42 of retainer 44. Consequently when the deceleration force incident to a major flight-impact overcomes the force of spring 34 the outward pressure of balls 4| against surface 42 of retainer 44 practically ceases. Consequently there need be no forward motion of the fuse in order to free surface 42 of retainer 44 from the outward pressure of balls 4| due to the wedge-like action of groove 39 upon balls 4|, since such wedge-like action is caused by the lforce of spring 34 tending to 'move the fuse-carrying unit rearwardly. The freeing of balls 4| from contact with shoulder 40 relieves surface 42 of retainer 44 from any action thereon by balls 4| dueto compressed spring 34,

whereupon relatively light deceleration force is sufficient, during the period that shoulders 21 and 3| remain in contact, or during the period that the deceleration force overcomes the action of spring 34, to move retainer 44 forward to the 4| are free to roll from groove 39 into cavity 43,

thereby leaving the member 30 free to begmoved substantially longer period of time than such deceleration force incident to a major flight-impact with lighter armor. This dierence in deceleration force varies the period, with armors of different resistances, that such deceleration force overcomes the normal force of restrained spring 34 as well as correspondingly varies the period of time that shoulders 21 and 3| remain in contact; and it is only when such deceleration force ceases to overcome the force of spring 34 that .the fuse-'carrying unit may be moved rearwardly with its pin 36 sliding in key-ways 3i until detonating cap I8 is brought into contact with firing pin 16 by the released force of spring 34, which initiates the detonation and delagration of the fuse, as hereinbefore explained, which position is shown in Figure 4, with the centrifugal force of the projectile causing segments 46 to lock against shoulder 41, Figure 2, and maintain the fuse-carrying unit in that position, wherein for the first time since the manufacture and assembly of the projectile the outlets |22 of the fuse unit are brought into communication with caps 29 of booster charges E6 so that upon the completion of the detonation the booster charges -66 as well as the explosive content of the projectile may be detonated.

It will thus be apparent that the initiation of detonation of the fuse is variably delayed according to the resistance characteristics of the armor which the projectile penetrates.

Additional variable delay is accomplished in the instance shown in the drawings, by the deceleration force incident to a major night-impact forcing the tapering forward end of tube |02 to different depths into and/or through the opening in bushing |00. Tube |02 being thus driven forward by, and relative to, the force incident to a major flight-impact of the projectile, such forwardA movement will be less when such major flight-im-V greater resistance. The ring pin 16 contacting with detonating cap H8 initiates the deflagration of vthe rear edge of the deflagrating tube |05 which continues `for a period of time variable to the extent to which tube |02 may be driven forwardly into its bushing |00, and the radial openings |04 through the walls of tube |02 are thus forced to correspondingly variable distances forwardly of the rear edge of deagrating tube |05. This varies the period in which tube |05 may deiiagrate before the deagration is communicated through openings |04 to tube |02 and thence to the elements 92, |2| and |22 of the fuse and thence to the booster charges 69 and the explosive content of the shell.

The spring 34 is designedly of such force when held under compression by the fuse unit that such force will be overcome only by the deceleration force incident to a major night-impact.

The tapering forward end of tube |02, with its coacting tapered opening in the forward end of bushing |00, are designedly of -such relative proportions that the deceleration force incident to a vmajor impact will drive tube |02 into said collar substantially proportionate to the magnitude of such deceleration force, which varies with armors of different resistances, and thus varies the deagrating period required for tube 405 to burn down to openings |04 of tube |02.

sense? The initiation of detonation of can H3 isvariablyi delayed due to' the varying."pc.. that the deceleration force: of the projectile ini piercing armors of. different resistance .characteristics-,- which', withithe variableperiod required for.' tube |05 t'oburn down to openings mit oftube H32,V is designednotto produce the' explosion'of the projectile until. itV has attained' a deiinite distance behind the armor .it has Ypierced'. This distancev may be;- varied for armors affording substantially the sameV deceleration to'like'projectiles by varying the` power' of spring .'i and/'or' varying the taper of.' tube' lfor the weight of tube m2, 'or' otherwise. i

It'wi'll be apparent that. the projectiles are all made and. uniformly assembled,V and that the variable delay in initiating detonation after the,

initial occurrencenoi a major night-impact,y as well as' the' Variable delaybetween: such initiation" andthe explosionof the projectiles are each occasioned not by anyV Variation in the manualadjustment oi any of' the parts butsolely by differ'- encesV in. the deceleration forces incident to the' different resistance characteristics of the armor encountered and' which may beunlmown to those initiating the flightV of the projectile or projectiles; It will be further apparent herefroin an'dlfrom' the instance shown in the exemplifying. apparatus that it' is the forceof the spring 3d whichdistinguishes between minor and major night-impacts of the projectile in. the sense. thatnriinorA such impacts do not, while major such impacts do, result in the initiation of detonation;V

Another valuable feature of my invention is that the force, for instance, of spring' 34 may be designed for different mediums With'which projectiles may minor flight-impact where such mediums affordI substantially less resistance than armor. Projectiles'designed to pierce heavy armor are usually different in caliber from those planned for piercing lighter armor and may be of diierent forces ci springs 3.4' whereby the former` in minor impact may encounter deceleration exceeding thatV ci' light arrnor and yet not explode until and unless'they achieve a major impact. However, the fuse units and projectiles may be of uniform sizesaste their threaded portions; and asY to the exterior size of units. so that by the substitution of a lighter unitV aprojectile for heavy armor may pierce relatively light armor and explode its greater explosive content the requisite distance behind or within the'same".

The cups 29 in the inner mouths of openings' prevent any tendency of booster explosive charges 65 to corrode or otherwise impair theV sliding' bearing of fuse unit portion tuin body' i8;

The fuse, and the booster or other explosive contentv being maintained out of communication with each other until an explosion of the projectile is designed to occur, substantially' contributes torthe safety of the projectile underV all' other conditions.

My method provides certainty in the region`Y where the projectile is explodabl'e regardless" o.'

its minor impacts; that its cxempliiyin'g: apparatus affords standard construction and' assembly which is safe in handling and under allcri'cumstances (except extreme heat) until after amajor impact; and that the requisite adjustments ofthe parts are occasioned by the characteristics ofthe major impact to variably d-eterrrnine the piacelof" explosionof theprojectile.

I have-.herein described my method together' with its exemplifying apparatus which I"now consider to represent the-best embodiment of my invention'. to obtain the most advantageous results, but I desire to have it understoodand appreciatedithat the apparatus shown is only illustrativef and: that my method may be advantageously practiced by other means which may be readily selected and: adapted by those skilled in the artafter becoming familiar with my method; andthatthexmethod and apparatus features of my' invention ink their' basic contemplation are entitled. tof-a broad range of equivalents. Furthermore; while itA is Vdesigned in the obtainance of the-'most satisfactory results to employ the various steps, features and elements of my method and` apparatus in thev combination and relations. described, many of these may be separately' usedg. altered or omitted without interfering Withfthemore kgeneral resultY or results indicated, and that my invention contemplates and extends thereto.

I claim:

l'lhe method of controlling the explosion of a projectile havingan explosive content and a fusdfcomprising the step of compacting the deilagrating material of.v the 'fuse' proportionately to the'deceleration forceencountered by the projectile in its flight.

2..-In a .projectile fuse unit; an' axial-ly bored fuse: body memberhaving aV reduced portion at its'V forward"V end: and an annulargroove insaid portion; vthere lbeing a. plurality of apertures throughfsaid reduced portion" adjacent said groove; thef'bre therein being large.V in the larger portion and; smaller in vsaid reduced portion and constrictedtherebetwe'en, means closing the for- -Wardf end of'sadb'cife; deilagra'ting pellets inV said Ward. end ther-aofi throughfthe greater part of the lengtho saidv member: and laterally extending' apertures. outwardly therefrom; deflagrating material; inY said bushing around said apertures, al sleeve. having a closed end. disposed against said'bushing, therebeing an annular groove in theouter lane of saidfendadjacent the deilagrating material'in saidsle'eve and aperturedwasher disposed against therearr end of said sleeve, a primer' disposed' against said washer, a plurality of arcuate segment members mounted disposed in an external'."grooveadjacentv the rear end of said body' membery: ar substantially hollow enclosing'nremberin which said body member is mounted, the'opening therein having a constricted portiorrrin which the'reduced end of said body memberisslidable, there being outwardly flaringk apertures opening into. said constricted portion-f i'gnitiorrtransmitting closuresI in the inner' ends? of said apertures, booster charges n said apertures; aspring under compression disposed; infthe enclosing memberfaround said-body member, toV exert. YbackwardlyV directed pressure againstv saidbody; alsh'oulder' in: said enclosing member" engageablefby'said arcuate segments when said4 body"n1ember\'is moved rearwardly to the 'ring position: a' base member engaged with andi` in partv extending.intov saidenclosing member; a firing; pinslidablymounted in said base and movable.l forwardly toia. position: such that saidprimermay'be' struckthereby, centrifugally 13 releasable means to hold said ring pin in a retracted position, balls disposed to be movable to lock said pin in the projected position, a keeper slidably mounted in the forward end of said enclosing member, there being a recess in the rear end of said enclosing member, there being a recess in the rear end of said keeper, arcuate segments mounted in an external groove in said keeper, a shoulder in said enclosing member engageable by said segments in said keeper when said keeper is moved forwardly, balls normally retained by said keeper in the groove in the forward end of said fuse body but movable into the said recess in said keeper when said keeper is moved forwardly, a cup member connected to the forward end of said enclosing member and into which the forward end of said keeper is movable, centrifugally releasable means to hold said keeper in the ball retaining position, and a thin metal shell enclosing said cup member and said enclosing member to a line rearwardly of said booster charges.

3. In a projectile fuse unit, enclosing means, booster charges disposed therein, a fuse including a primer slidably mounted in said means, said fuse having an annular groove adjacent its forward end, balls normally disposed in said groove, a keeper disposed to retain said balls in said groove, centrifugally releasable means to lock said keeper in the ball retaining position, means to lock said keeper out of said ball retaining position, a ring pin, centrifugally releasable means to hold said pin normally in a retracted position, means to hold said pin in a projected position, and means to move said primer back into detonating contact with said pin upon cessation of a decelerating force after said keeper has been moved to release said balls and said pin has been moved into the projected position, the said movement of the fuse being eiective to move said fuse into position to deflagrate said booster charges.

e. In a projectile fuse unit, enclosing means, a fuse including a primer slidably mounted therein, means to hold said fuse normally in an operative position, said holding means being adapted to be released by centrifugal force and for impact of the projectile, means to move said fuse when so released, a firing pin having a conical head and a shoulder, said head being movable in a recess having a conical end wall, balls normally disposed in a recess that cornmunicates With the said conical end of the aforesaid recess and adapted to move out into the aforesaid recess when said pin is projected, and

centrifugally releasable means engaging the shoulder on said pin to hold said pin in a retracted position, said pin being movable into a projected position by the deceleration of the projectile to detonate said primer when said fuse is moved by the said fuse moving means, said fuse being in position to deflagrate a charge outside said means when in the primer detonating position.

5. In a projectile fuse-un.it, enclosing means, booster charges carried thereby, a fuse including a primer slidably mounted therein normally out of position to deagrate saidl charges, means to lock said fuse in the said position releasable by centrifugal force and deceleration of the projectile, means to move said fuse into position to deflagrate said charges after said fuse is so released, means to detonate said primer when said fuse'is so moved, compacted deflagratable material in the train of said fuse, relatively loose compactable deflagratable material in said train, a second body of compacted delagratable material disposed to be deagrated by said primer, and a member in said fuse variably movable proportionately to the deceleration of the projectile to compact said loose material in proportion to its movement and establish variable communi! cation between said loose material and said second body of compacted material proportionately to the movement of said member.

6. The method of controlling the explosion of a projectile having an explosive content and fuse, comprising the steps of providing relatively loose deflagrating material in the fuse and compacting said material proportionately to the deceleration force acting on the projectile in its flight.

7. In a projectile fuse unit, enclosing means, booster charges disposed therein, a fuse including a primer slidably mounted in said means, said fuse having an annular groove adjacent its forward end, balls normally disposed in said groove, a keeper disposed to retain said balls in said groove, centrifugally releasable means to lock said keeper in the ball retaining position, means to lock said keeper out of said ball retaining position, a firing pin operative to detonate said primer, and means to move said fuse to make primer detonating contact with said pin upon cessation of a decelerating force after said keeper has been moved to release said balls from said groove.

HARRY J. NICHOLS.

REFERENCES CTED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 475,786 Merriam May 31, 1892 999,470 Semple Aug. 1, 1911 1,310,046 Asbury July 15, 1919 1,545,139 Greenwell July 7, 1925 1,865,802 Towner July 5, 1932 FOREIGN PATENTS Number Country Date 5,284 Great Britain 1911 207,021 Great Britain Nov. 22, 1923 221,321 Great Britain Aug. 17, 1925 

